I get the same thing all the time. I don’t know why, but it happens to me, too. It’s actually rather annoying, since, if I’m logged into my.studiopress.com, shouldn’t it also log me into the forum by default?

I get the little message that I don’t have permission, but when I refresh the page after logging in, I’m always logged in. I will bookmark the login recommended by Nick to see if that ‘takes’. Otherwise, I know how to get in.